We acknowledge the Virginia Military Institute (VMI) Department of Chemistry for support of electrochemical experiments and instrumentation (L.S.C. and J.T.H.). The VMI Office of the Dean of Faculty supported production fees associated with JoVE publications. We acknowledge the UNC EFRC: Center for Solar Fuels, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001011, for support of compound synthesis and materials characterization (D.P.H).

1. Synthesize 1
Synthesize&#160;1 (PhTpy is 4&#39;-phenyl-2,2&#39;:6&#39;,2&#39;&#39;-terpyridine; 5,5&#8217;-dvbpy is 5,5&#39;-divinyl-2,2&#39;-bipyridine; Figure 4) according to the procedure outlined previously.18
2. Prepare 1.3 mM Monomer Solution of 1 in an Electrolyte Solution
<ol>
	<li>Prepare a 0.1 M stock electrolyte solution of tetra-n-butylammonium hexafluorophosphate, TBAPF6, in acetonitrile, MeCN.
	<ol>
		<li>Place MeCN over activated 3 &#197; molecular sieves, or K2CO3, for 24 hr to remove adventitious H2O.</li>
		<li>Place TBAPF6 (0.969 g, 2.50 mmol) in a 25.00 ml flame dried volumetric flask.</li>
		<li>Filter the molecular sieve or K2CO3 particulates from the dried MeCN and bring the 25.00 ml volumetric flask containing TBAPF6 to volume.</li>
	</ol>
	</li>
	<li>Place 1 (0.0049 g, 5.2 x 10-6 mol) in and dry 4 dram vial or a 10 ml round bottom flask and add 4.00 ml of the stock solution of 0.1 M TBAPF6 in MeCN.</li>
	<li>Transfer 3.5-4.0 ml of the red-orange colored electrolytic solution of 1 into the central compartment of a 3-compartment cell, with each compartment separated by a medium porosity glass frit.</li>
	<li>Quickly fill the outer compartments of the 3-compartment cell to an equal height as the central compartment stock solution, with some of the remaining dry 0.1 M TBAPF6 in MeCN to prevent leakage to the outer compartments. Note: Time is an important factor because solutions in the different compartments will slowly mix and significantly change the concentration of the main compartment if the solvent heights are not the same.</li>
</ol>
3. Electropolymerize 1 on a 3 mm Diameter Glassy Carbon Electrode or a 1.0 cm2 FTO Electrode
<ol>
	<li>Prepare septa for nitrogen/argon degassing tubes and for electrodes.
	<ol>
		<li>Cut a slit into each of the 3 rubber septa and guide a thin polytetrafluoroethylene, PTFE, tube through the slit.</li>
		<li>Slide the Ag/AgNO3 reference electrode through one of the septa, place the reference electrode/PTFE tube/septum in one of the outer compartments, and seal the compartment with the septum.</li>
		<li>Guide the platinum wire/gauze counter electrode through a different septum place the platinum wire/PTFE tube/septum in one of the outer compartments, and seal the compartment with the septum. If the slit is not sufficiently large or wire sufficiently stiff to prevent bending the wire, use a wide bore needle to guide the platinum wire counter electrode through the septum.</li>
		<li>Guide a freshly polished 3 mm glassy carbon electrode through the remaining septum and place it such that the electrode is suspended in the solution or, for an FTO slide, guide a wire connected to an alligator clip through the septum, then clamp the FTO slide with the alligator clip and make sure that the conductive side of the slide is perpendicular to the counter electrode when submerged.
		<ol>
			<li>Prior to inserting the glassy carbon electrode: polish the glassy carbon by placing alumina (0.5 &#956;m) on a wetted polishing pad, then, move the electrode in a figure-8 motion for 30 sec while holding the electrode perpendicular to the pad &#8212; to polish all sides of the electrode evenly &#8212; and rinse any remaining alumina off with a H2O water squirt bottle followed by an MeCN squirt bottle rinse.</li>
			<li>Prior to clamping the FTO slide: wrap several layers of non-conductive Kapton tape around the center part of a 30 x 10 mm FTO slide such that a 10 x 10 mm portion of the slide is exposed.</li>
			<li>Collect a UV-Vis spectrum of the FTO slide by placing/holding the FTO slide in a position in the beam path of the spectrometer that has been predetermined to ensure consistency.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>De-aerate the solutions in the 3-compartment electrochemical cell.
	<ol>
		<li>Connect one end of Tygon tubing to the nitrogen/argon supply and connect the other end to a gas washer containing MeCN.</li>
		<li>Cut another piece of Tygon tubing, connect one end to the outflowing MeCN washed nitrogen/argon, and connect the other end to a 4 way splitter.</li>
		<li>Connect the PTFE tubes to the 3 remaining connections of the 4 way splitter.</li>
		<li>Submerge the PTFE tubes into the solutions in each of the compartments and turn on the flow of nitrogen/argon such that a rapid bubbling of the solution commences.</li>
		<li>Continue de-aerating the solution for 5-10 min, then pull the PTFE tubes just above the surface of the solution, leaving the flow of nitrogen/argon on in order to keep a positive pressure of inert gas on the system and to prevent solution convection caused by bubbling.</li>
	</ol>
	</li>
	<li>Perform electrochemical experiments.
	<ol>
		<li>Connect electrodes from the potentiostat to the appropriate electrodes in the 3&#8209;compartment cell.</li>
		<li>Perform a cyclic voltammetry, CV, experiment with the following parameters: switching potentials = 0 V and -1.81 V; scan/sweep rate = 100 mV/sec; number of cycles = 5.</li>
		<li>When the CV experiment is complete, remove the working (glassy carbon or FTO) electrode from the polymerization solution and gently rinse the surface of the electrode with MeCN from a pipette or a squirt bottle to remove any remaining monomer solution.</li>
	</ol>
	</li>
</ol>
4. Surface Coverage Determination
<ol>
	<li>Place the rinsed working electrode in a freshly prepared solution of 0.1 M TBAPF6/MeCN in an electrochemical cell containing a counter electrode and a reference electrode (preferably the same reference electrode used in the electropolymerization).</li>
	<li>Perform a cyclic voltammetry, CV, experiment with the following parameters: switching potentials = 0 and +1.5 V; scan/sweep rate = 100 mV/sec; number of cycles = 15.</li>
	<li>Integrate the charge under the anodic and cathodic peaks for the adsorbed electropolymer Ru(III/II) couple, average the charge under the anodic and cathodic peaks, and using Equation 1 determine the surface coverage.</li>
	<li>For the FTO slide: place/hold the FTO slide in the predetermined position in front of the UV-Vis sample holder such that the beam-path passes through the colored film. The FTO slide can be wet or dry but make comparisons under the same conditions as the blank spectra was collected under.</li>
	<li>Subtract the spectrum obtained for the FTO spectrum that was collected for that particular slide prior to electropolymerization from the spectrum of the film-on-FTO in order to produce an absorption spectrum for the film itself.</li>
</ol>

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	<li>Abru&#241;a, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coordination+chemistry+in+two+dimensions:+chemically+modified+electrodes.">Coordination chemistry in two dimensions: chemically modified electrodes.</a> Coordination Chemistry Reviews. 86, 135-189 (1988).</li><li>Waltman, R. J., Bargon, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrically+conducting+polymers:+a+review+of+the+electropolymerization+reaction,+of+the+effects+of+chemical+structure+on+polymer+film+properties,+and+of+applications+towards+technology.">Electrically conducting polymers: a review of the electropolymerization reaction, of the effects of chemical structure on polymer film properties, and of applications towards technology.</a> Canadian Journal of Chemistry. 64, 76-95 (1986).</li><li>Zhong, Y. -. 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No conflicts of interest declared.

Electropolymerization offers a large range of controllable variables that are not common to other techniques. In addition to standard reaction variables like reagent (monomer) concentration, temperature, solvent, etc., electropolymerization can be additionally controlled by electrochemical experiment parameters common to electrochemical methods. CV scan rates, switching potentials, and number of cycles affect the deposition of electropolymers. For example, as the number of cycles through the ligand reduction wav...

Electropolymerization is a polymerization technique that utilizes an applied potential to initiate the polymerization of monomeric precursors directly at the surface of an electrode and has been exploited to produce thin electroactive and/or photochemically active polypyridyl films on electrode and semiconductor surfaces.1-4 Electrocatalysis,5-10 electron transfer,11,12 photochemistry,13-16 electrochromism,17 and coordination chemistry18 have been investigated in electropolymerized films. This technique was first developed at the University of North Carolina in a Meyer-Murray collaboration for the electropolymerization of vinyl3,5,7,8,11-15,19,20 and pyrrole6,9,21-24 derivatized metal complexes on a variety of conducting substrates. Figure 1 presents a number of common pyridyl based ligands that, when coordinated to metal complexes, have produced electropolymers. In reductive electropolymerization, electropolymerization of vinyl containing compounds occurs upon the reduction of pyridyl ligands conjugated to vinyl groups, while with pyrrole-functionalized ligands, electropolymerization is initiated by oxidation of the pyrrole moieties, resulting in oxidative electropolymerization (Figure 2). Electropolymerization technology was developed with the goal of providing a generalized methodology for directly attaching virtually any transition metal complex to any electrode. The versatility of the method opens the door to numerous investigations of electropolymer modified electrodes.
In contrast to other attachment strategies, which involve direct bonding to the electrode, electropolymerization offers the advantage of not requiring electrode surface pre-modification. Therefore it can be applied to any number of conducting substrates, regardless of surface composition or morphology.4,10,25,26 This versatility is a result of changing physical properties as the polymer length grows; the monomers are soluble in the electrolytic solution but as polymerization occurs and cross-linking rigidifies the film, precipitation and physical adsorption the electrode surface occurs (Figure 3).27
Compared to oxide surface-bound carboxylate, which are unstable on oxide surfaces in water, or phosphonate-derivatized complexes, which are unstable at elevated pH&#39;s, commonly used in solar fuels research, these interfacial electrode-polymer film structures offer the added benefit of stability in a variety of media including organic solvents and water over a large pH range (0-14).28-30 Electropolymerization can also deposit films with large ranges of apparent surface coverages, from sub-monolayer to dozens or hundreds of equivalents monolayer, whereas carboxylate or phosphonate-derivatized complexes-interface structures are limited to monolayer surface coverages.
Although any number of vinyl or pyrrole containing pyridyl and polypyridyl compounds are capable of polymerization, [RuII(PhTpy)(5,5&#8217;-dvbpy)(MeCN)](PF6)2, (1; PhTpy is 4&#39;-phenyl-2,2&#39;:6&#39;,2&#39;&#39;-terpyridine; 5,5&#8217;-dvbpy is 5,5&#39;-divinyl-2,2&#39;-bipyridine; Figure 4) will be utilized as a model complex to demonstrate reductive electropolymerization on glassy carbon and fluorine-doped tin oxide, FTO, electrodes in this report. 1 is an example of a modern electropolymer precursor that has potential electrocatalytic applications and, due to its metal-to-ligand charge transfer, MLCT, absorption spectrum lying in the visible region of the light spectrum, can be investigated with UV-Vis spectroscopy.18,30 Please note that some results presented here for 1 have already been published in a slightly modified form.18

<table><tbody><tr><td>Tetrabutylammonium hexafluorophosphate for electrochemical analysis, &amp;ge;99.0%</td><td>Sigma-Aldrich</td><td>86879-25G</td><td></td></tr><tr><td>Acetonitrile&amp;nbsp;(Optima LC/MS), Fisher Chemical</td><td>Fisher Scientific</td><td>A955-4</td><td></td></tr><tr><td>3 mm dia. Glassy Carbon Working Electrode</td><td>CH Instruments</td><td>CH104</td><td></td></tr><tr><td>Non-Aqueous Ag/Ag&lt;sup&gt;+&lt;/sup&gt; Reference Electrode w/ porous Teflon Tip</td><td>CH Instruments</td><td>CHI112</td><td></td></tr><tr><td>Platinum&amp;nbsp;gauze</td><td>Alfa Aesar</td><td>AA10282FF&amp;nbsp;</td><td></td></tr><tr><td>Electrode Polishing Kit</td><td>CH Instruments</td><td>CHI120</td><td></td></tr><tr><td>Cole-Parmer KAPTON TAPE 1/2&amp;nbsp;IN x 36&amp;nbsp;YD</td><td>Fisher Scientific</td><td>NC0099200</td><td></td></tr><tr><td>Fisherbrand Polypropylene Tubing 4-Way Connectors</td><td>Fisher Scientific</td><td>15-315-32B</td><td></td></tr><tr><td>500 ml Bottle, Gas Washing, Tall Form, Coarse Frit</td><td>Chemglass</td><td>CG-1114-15</td><td></td></tr><tr><td>3-compartment H-Cell for electrochemistry</td><td>Custom made H-cell with 3 compartments</td><td></td><td></td></tr></tbody></table>

reductive electropolymerization of a vinyl-containing poly-pyridyl complex on glassy carbon and fluorine-doped tin oxide electrodes

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is one surface modification technique that electrodeposits a polymeric film at the surface of an electrode by utilizing an applied potential to initiate the polymerization of substrates in the Helmholtz layer. This useful technique was first established by a Murray-Meyer collaboration at the University of North Carolina at Chapel Hill in the early 1980s and utilized to study numerous physical phenomena of films containing inorganic complexes as the monomeric substrate. Here, we highlight a procedure for coating electrodes with an inorganic complex by performing reductive electropolymerization of the vinyl-containing poly-pyridyl complex onto glassy carbon and fluorine doped tin oxide coated electrodes. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization but are far less sensitive to oxygen and water.

Electropolymer growth is most easily recognized when observing the progress of the prescribed CV experiment (Protocol Text STEP 3.3.2). Figure 5 exemplifies electropolymer growth on a 0.071 cm2 (3 mm diameter) glassy carbon electrode with 1. The first cycle of the experiment produces a voltammogram roughly resembling that which is expected for a ruthenium solution of similar concentration (Figure 5, black trace) but upon successive cycles, through the 1st...

Watch this Scientific Journal Video about Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes at JoVE.com

Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes

A procedure for performing reductive electropolymerization of vinyl-containing compounds onto glassy carbon and fluorine doped tin-oxide coated electrodes is presented. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization.

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is ...

reductive-electropolymerization-vinyl-containing-poly-pyridyl-complex

Research

JoVE Journal

Chemistry

11.8K Views.  Virginia Military Institute. A procedure for performing reductive electropolymerization of vinyl-containing compounds onto glassy carbon and fluorine doped tin-oxide coated electrodes is presented. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization. 

Video: Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes

Patterning Cells on Optically Transparent Indium Tin Oxide Electrodes

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular constructs serving as in vitro mimics of native tissues.  In this study, photolithography and wet etching techniques were used to fabricate individually addressable indium tin oxide (ITO) electrodes on glass substrates.  The glass substrates containing ITO microelectrodes were modified with poly(ethylene glycol) (PEG) silane to make them protein and cell resistive.  Presence of insulating PEG molecules on the electrode surface was verified by cyclic voltammetry employing potassium ferricyanide as a redox reporter molecule.  Importantly, the application of reductive potential caused desorption of the PEG layer, resulting in regeneration of the conductive electrode surface and appearance of typical ferricyanide redox peaks.    Application of reductive potential also corresponded to switching of ITO electrode properties from cell non-adhesive to cell-adhesive. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.  Micropatterning of several cell types was demonstrated on these substrates.   In the future, the control of the biointerfacial properties afforded by this method will allow to engineer cellular microenvironments through the assembly of three or more cell types into a precise geometric configuration on an optically transparent substrate.

Non-fouling PEG silane monolayer was desorbed from individually addressable ITO electrodes on glass by application of a reductive potential. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular ...

Biology

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT).

A protocol is presented for the synthesis and preparation of nanoparticles consisting of electroactive polymers.

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step ...

Engineering

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal inks. For the photoactive absorber layer, colloidal CdTe and CdSe nanocrystals (3-5 nm) are synthesized using an inert hot injection technique and cleaned with precipitations to remove excess starting reagents. Similarly, gold nanocrystals (3-5 nm) are synthesized under ambient conditions and dissolved in organic solvents. In addition, precursor solutions for transparent conductive indium tin oxide (ITO) films are prepared from solutions of indium and tin salts paired with a reactive oxidizer. Layer-by-layer, these solutions are deposited onto a glass substrate following annealing (200-400 &#176;C) to build the nanocrystal solar cell (glass/ITO/CdSe/CdTe/Au). Pre-annealing ligand exchange is required for CdSe and CdTe nanocrystals where films are dipped in NH4Cl:methanol to replace long-chain native ligands with small inorganic Cl- anions. NH4Cl(s) was found to act as a catalyst for the sintering reaction (as a non-toxic alternative to the conventional CdCl2(s) treatment) leading to grain growth (136&#177;39 nm) during heating. The thickness and roughness of the prepared films are characterized with SEM and optical profilometry. FTIR is used to determine the degree of ligand exchange prior to sintering, and XRD is used to verify the crystallinity and phase of each material. UV/Vis spectra show high visible light transmission through the ITO layer and a red shift in the absorbance of the cadmium chalcogenide nanocrystals after thermal annealing. Current-voltage curves of completed devices are measured under simulated one sun illumination. Small differences in deposition techniques and reagents employed during ligand exchange have been shown to have a profound influence on the device properties. Here, we examine the effects of chemical (sintering and ligand exchange agents) and physical treatments (solution concentration, spray-pressure, annealing time and annealing temperature) on photovoltaic device performance.

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

Sensing of Barrier Tissue Disruption with an Organic Electrochemical Transistor

The gastrointestinal tract is an example of barrier tissue that provides a physical barrier against entry of pathogens and toxins, while allowing the passage of necessary ions and molecules. A breach in this barrier can be caused by a reduction in the extracellular calcium concentration. This reduction in calcium concentration causes a conformational change in proteins involved in the sealing of the barrier, leading to an increase of the paracellular flux. To mimic this effect the calcium chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N&#39;,N&#39;-tetra acetic acid (EGTA) was used on a monolayer of cells known to be representative of the gastrointestinal tract. Different methods to detect the disruption of the barrier tissue already exist, such as immunofluorescence and&#160;permeability assays. However, these methods are time-consuming and costly and not suited to dynamic or high-throughput measurements. Electronic methods for measuring barrier tissue integrity also exist for measurement of the transepithelial resistance (TER), however these are often costly and complex. The development of rapid, cheap, and sensitive methods is urgently needed as the integrity of barrier tissue is a key parameter in drug discovery and pathogen/toxin diagnostics. The organic electrochemical transistor (OECT) integrated with barrier tissue forming cells has been shown as a new device capable of dynamically monitoring barrier tissue integrity. The device is able to measure minute variations in ionic flux with unprecedented temporal resolution and sensitivity, in real time, as an indicator of barrier tissue integrity. This new method is based on a simple device that can be compatible with high throughput screening applications and fabricated at low cost.

The Organic Electrochemical Transistor is integrated with live cells and used to monitor ion flux across the gastrointestinal epithelial barrier. In this study, an increase in ion flux, related to disruption of tight junctions, induced by the presence of the calcium chelator EGTA (ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetra acetic acid), is measured.

The gastrointestinal tract is an example of barrier tissue that provides a physical barrier against entry of pathogens and toxins, while allowing the ...

Bioengineering

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

Solution-Processed "Silver-Bismuth-Iodine" Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. However, poor surface morphologies and relatively high bandgap energies have limited their potential. Silver-bismuth-iodine (Ag-Bi-I) is a promising semiconductor for optoelectronic devices. Therefore, we demonstrate the fabrication of Ag-Bi-I ternary thin films using material solution processing. The resulting thin films exhibit controlled surface morphologies and optical bandgaps according to their thermal annealing temperatures. In addition, it has been reported that Ag-Bi-I ternary systems crystallize to AgBi2I7, Ag2BiI5, etc. according to the ratio of the precursor chemicals. The solution-processed AgBi2I7 thin films exhibit a cubic-phase crystal structure, dense, pinhole-free surface morphologies with grains ranging in size from 200 to 800 nm, and an indirect bandgap of 1.87 eV. The resultant AgBi2I7 thin films show good air stability and energy band diagrams, as well as surface morphologies and optical bandgaps suitable for lead-free and air-stable single-junction solar cells. Very recently, a solar cell with 4.3% power conversion efficiency was obtained by optimizing the Ag-Bi-I crystal compositions and solar cell device architectures.

Herein, we present detailed protocols for solution-processed silver-bismuth-iodine (Ag-Bi-I) ternary semiconductor thin films fabricated on TiO2-coated transparent electrodes and their potential application as air-stable and lead-free optoelectronic devices.

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. ...

An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation

We demonstrate a method for fabricating a prototype reflective display device that contains cholesteric liquid crystal (LC) as an active component. The cholesteric LC is composed of a nematic LC 4&#39;-pentyloxy-4-cyanobiphenyl (5OCB), redox-responsive chiral dopant (FcD), and a supporting electrolyte 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIm-OTf). The most important component is FcD. This molecule changes its helical twisting power (HTP) value in response to redox reactions. Therefore, in situ electrochemical redox reactions in the LC mixture allow for the device to change its reflection color in response to electrical stimuli. The LC mixture was introduced, by a capillary action, into a sandwich-type ITO glass cell comprising two glass slides with patterned indium tin oxide (ITO) electrodes, one of which was coated with poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol) doped with perchlorate (PEDOT+). Upon application of +1.5 V, the reflection color of the device changed from blue (467 nm) to green (485 nm) in 0.4 s. Subsequent application of 0 V made the device recover the original blue color in 2.7 s. This device is characterized by its fastest electrical response and lowest operating voltage among any previously reported cholesteric LC device. This device could pave the way for the development of next generation reflective displays with low energy consumption rates.

A protocol for the fabrication of a reflective cholesteric liquid crystalline display device containing a redox-responsive chiral dopant allowing quick and low-voltage operation is presented.

We demonstrate a method for fabricating a prototype reflective display device that contains cholesteric liquid crystal (LC) as an active component. The ...

Electrochemical Preparation of Poly(3,4-Ethylenedioxythiophene) Layers on Gold Microelectrodes for Uric Acid-Sensing Applications

Two different methods for the synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on gold electrodes are described, using electropolymerization of 3,4-ethylenedioxythiophene (EDOT) monomer in an aqueous and an organic solution. Cyclic voltammetry (CV) was used in the synthesis of PEDOT thin layers. Lithium perchlorate (LiClO4) was used as a dopant in both aqueous (aqueous/acetonitrile (ACN)) and organic (propylene carbonate (PC)) solvent systems. After the PEDOT layer was created in the organic system, the electrode surface was acclimatized by successive cycling in an aqueous solution for use as a sensor for aqueous samples. 
The use of an aqueous-based electropolymerization method has the potential benefit of removing the acclimatization step to have a shorter sensor preparation time. Although the aqueous method is more economical and environmentally friendly than the organic solvent method, superior PEDOT formation is obtained in the organic solution. The resulting PEDOT electrode surfaces were characterized by scanning electron microscopy (SEM), which showed the constant growth of PEDOT during electropolymerization from the organic PC solution, with rapid fractal-type growth on gold (Au) microelectrodes.

Electrochemical Preparation of Poly3,4-Ethylenedioxythiophene Layers on Gold Microelectrodes for Uric Acid-Sensing Applications

We describe aqueous and organic solvent systems for the electropolymerization of poly(3,4-ethylenedioxythiophene) to create thin layers on the surface of gold microelectrodes, which are used for sensing low molecular weight analytes.

Two different methods for the synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on gold electrodes are described, using electropolymerization of ...

Development of Efficient OLEDs from Solution Deposition

The use of highly efficient organic emitters based on the thermally activated delayed fluorescence (TADF) concept is interesting due to their 100% internal quantum efficiency. Presented here is a solution deposition method for the fabrication of efficient organic light-emitting diodes (OLEDs) based on a TADF emitter in a simple device structure. This fast, low-cost, and efficient process can be used for all OLED emissive layers that follow the host-guest concept. The fundamental steps are described along with necessary information for further reproduction. The goal to establish a general protocol that can be easily adapted for principal organic emitters currently under study and development.

Presented here is a protocol for the fabrication of efficient, simple, solution-deposited organic light-emitting diodes with low roll-off.

The use of highly efficient organic emitters based on the thermally activated delayed fluorescence (TADF) concept is interesting due to their 100% ...

Vapor Phase Deposition of Electroactive Poly(3,4-ethylenedioxythiophene) onto Electrospun Commodity Polymer Nanofibers

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for applications in water purification, electrocatalysis, and biomedicine. The uniformly white PAN nanofiber mats were cut into 2 cm x 2 cm coupons to ensure consistency. After electrospinning, these nanofibers were coated with an electroactive polymer (EAP) using chemical vapor deposition, with iron (III) chloride (FeCl3) serving as an oxidant for polymerizing 3,4-ethylenedioxythiophene (EDOT) into poly(3,4-ethylenedioxythiophene) (PEDOT). The study examined the impact of different FeCl3 concentrations on PEDOT deposition on the PAN coupons. PEDOT deposition led to an increase in coupon weight. Scanning electron microscopy (SEM) revealed increases in the diameter of the nanofibers treated with increasing FeCl3 oxidant concentration, although higher FeCl3&#160;concentrations caused inter-fiber bridging, implying a concomitant decrease in inter-fiber spacing. Energy dispersive X-ray spectroscopy (EDS) was used to confirm the presence of Fe, Cl, and S in the nanofibers, with sulfur content rising with FeCl3&#160;concentration used, suggesting increased PEDOT deposition efficiency with increasing oxidant concentration. Mechanical testing showed that PEDOT-coated PAN fibers had improved tensile strength and toughness in the hydrated state compared to pure PAN nanofibers. These results highlight the crucial role of FeCl3&#160;concentration in influencing the morphology and properties of PAN-PEDOT composites, enhancing their suitability for applications such as water purification, tissue engineering, biosensing, catalysis, and energy storage.

This paper describes a simple technique for coating electrospun PAN nanofibers with electroactive polymers using vapor deposition. The effects of the oxidant FeCl&#8323; on the deposition of poly(3,4-ethylenedioxythiophene) coatings on PAN were investigated to understand and optimize polymer growth, fiber diameter, and overall mechanical strength of the nanofiber mats.

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for ...